Method Character Limit?

I was wondering if there is a maximum length for stings in the text to be replaced box.

I found one day that a replace method I had been using as a catch all for stings I wanted to remove from filenames I was renaming on a regular basis had grown to 10102 characters.

For some reason the text in the text box is now invisible. This wasn't the case for ANY of the other 339 methods in the batch so I know it had to do specifically with THAT string.

I tried deleting the contents of the box and replacing it.
I tried removing THAT instance of Replace method, saved without the contents of that box, restarted AR then re-added the contents to the box but the info was still invisible.
I then tried adding it back a bit at a time to see if it was a maximum characters limitation or something I had entered in the box that was making it behave this way. It turns out it was the number of characters because when I reached a certain point the info disappeared again.

I just did a test and it turns out the magic number of characters was 6296 and then the text in the box disappears.

This doesn't make any sense to me because I have been using this exact method for ages adding to it a bit at a time and it has never been invisible before. And there are 10102 characters in the box. But I just tried it on another machine and it did the same thing however this time it disappeared at 5442 characters. I may have combined the contents of 2 different catch all boxes the last time I used them I can't remember. But that may explain why It never happened before.

This has me thinking it's gotta be something else but for the life of me I can't figure out what. I know the app can't have different limitations since I am using the same OS on both machines ... wait I just noticed I'm using a different version of AR on the machines the more recent one 3.65 actually disappears with less characters than the older version.

So anyway I said all that so I could say this... Is there an actual limitation to the number of characters you can use in a replace method?